The objective of the DNA Microarray and Bioinformatics Core Service is to use DNA microarray technology to rapidly and comprehensively determine the effects of anticancer agents on the patterns of gene expression in small samples of human minor cells, and to compare these patterns with reference patterns of gene expression that are produced by the same drugs in model in vitro and in vivo systems, cell culture and human tumor xenografts. The hypothesis upon which this approach is based is that the pattern of changes in gene expression can be used as a surrogate endpoint for 4mg effects; a reference pattern will be derived from the patterns of changes in gene expression which are produced in the model systems. The Core Service will use state of the art DN microarray equipment that is part of an established microarray facility at the Arizona Cancer Center. This includes all the necessary equipment for arraying, hybridizing and reading human gene chips; bacterial clone libraries for the production of microarray probes; and equipment for automating the PCR-based preparation of those probes. In addition, the protocols for the proposed work have been implemented and refined at the Arizona Cancer Center. The Bioinformatics support for this process will use current generation computing and communication technologies to store, manage, integrate and analyze the data from the microarray analyses.